Chilling: Cold Snaps Will Persist in Warming World

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Although the planet is warming overall, events of extreme cold
are still likely to persist on each continent for the next
century, researchers say.

The Southeast and Northwest in the United States may be
especially vulnerable to these chills, scientists added.

Investigators at Oak Ridge National Laboratory used nine global
climate models assuming moderate levels of greenhouse gas
emissions (the gases that build up in the atmosphere and trap
heat) to compare the climates of 1991 to 2000 with 2091 to 2100.

All nine models found that climate would overall experience
warming at the end of the century. However, they forecast that
events of extreme cold would still happen, although they
would occur less frequently.

"The fact that future extreme cold events will continue to be at
least as intense and long-lasting in many regions of the world,
even under warming scenarios, may not seem intuitive," researcher
Auroop Ganguly, a civil and environmental engineer at Oak Ridge
National Laboratory, told OurAmazingPlanet.

One can think of the existence of extreme cold events despite an
overall
trend of global warming much as one would the presence of
millionaires in the midst of the Great Depression or the current
global economic crisis. Global warming and the Great Depression
represent average trends, while cold snaps and millionaires
represent extreme cases within those trends.

"Global warming happens over and above natural climate
variability, and the latter may cause cold snaps on any given
winter and at specific regions of the world even though the
overall longer-term global trend is one of warming," Ganguly
said.

In addition, "as others have said previously, global warming is
probably better understood as 'global weirding' — for example,
the changes in temperature patterns are expected to have
significant geographical variability," he added.

And global warming is of course not the only factor determining
the temperatures at a particular place and time.

"Climate and weather are governed by complex physical mechanisms
related to, for example, topography, atmospheric movements and
ocean currents, and warming in one region may actually lead to
cold extremes in others," Ganguly explained.

Although the researchers found that the Southeast and Northwest
may be especially prone to persistence of extreme cold events,
they cannot yet pinpoint why, Ganguly said. "We may be able to
speculate, based on the related scientific literature, that
topography, natural climate variability, atmospheric blocking
effects and
ocean warming all play a role," he said.

These findings suggest that regional plans in the face of climate
change "cannot afford to relax readiness for extreme cold events
even as preparations are made to adapt to a generally warming
world," Ganguly said.